Avengers fanart: Catnap in the sun

I'm going to put this on Tumblr in the morning, but I wanted to let it sit overnight and look over it again before releasing it into the wild, since you can't easily tweak things once something's been Tumblr-posted. But there's no reason why I can't post it here right now!

( Prompt and art under the cut - maybe a little CA2 spoilerage around the edges, no content warnings; Steve, Natasha, Bucky )